Multiple-expansion steam turbine



Feb. 27, 1923.

MULTIPLE EXPANSION STEAM TURBINE- FILED AUG- II, I921. 2 SHEETS-SHEET I.

11 11 5 l 9 9' o I 5 15 I I II 5 I I 7 I 1 1,446,840. R. DE POTTER.

a. m: POTTER.' MULTIPLE EXPANSION STEAM TURBINEn Feb. 27, 1923.

2 SHEETS SHEET 2- FlLED AUG. I7, 1921.

Z' EGQ I ii:

Patented Feb. 27, 1923.

UNITED STAT ROGER DE POTTER, OE'ANTWERP, BELGIUM.

MULTIPLE-EXPANSION STEAM TURBINE.

Application filed August 17, 1921. 'Serial No. 498,091.

T 0 all whom it mag concern:

Be it known that 1, Room on POTTER, a subject of the King of the Belgians, residing at Antwerp, Belgium, have invented a certain Improved Multiple-Expansion Steam Turbine, of which the following is a specification. v

The present invention relates to a multiple expansion steam-turbine and has for its object to provide an improved type of turbine wherein the steam is utilized more advantageously than has been the case previously, mainly owing to an improved arrangement of buckets. The turbine forming the subject matter of the present 111- vention is also easier of construction'than the existing types.

In order to facilitate the descriptlon of the invention, an embodiment of the same is, by way of example only, illustrated by the accompanying drawings, wherein:

Figure 1 shows a front view of the 1mproved turbine, with one of the lateral walls of the turbine casing plartially removed in order better to show t e internal arrangement, 4

Figure 2 shows a longitudinal elevation of the said turbine, the upper cover of the casing having been partially removed.

Fig. 3 is'a detached detail view of an obturator forming a part of the aforesaid turbine and its operating device, looklng from above.

In the turbine forming the subject matter ofthe present invention, the steam is admitted by means of one of the conical nozzles 10. These nozzles are divided in two portions 18 and 19 of gradually increasing cross section. A slide valve 15 slidlng in lateral grooves opens or closes successively the opening of the nozzles 18 and 19 according to the power required: This slide valve 15 is provided with a rack meshing with a tooth-wheel iii-operated by means of a hand wheel 17. The same device for the admission of steam is employed when it is desired that the turbine should rotate in the reverse direction. The steam is admitted under the rotor 3 on a bucket wheel where it expands by passing alternately into the upper and lower buckets (those of the bucket wheel 7 and those of a corresponding series of stationary buckets 8 provided on the inner periphery of the casing respectively). After having passed through this first circle of buckets the steam passes by way of a pasthe velocity of the steam: this condition is fulfilled in the present turbine owing to the multiple circumferential expansions of the steam.

The 4 bucket-wheels and corresponding series of stationary buckets on the casin are all of the same diameter, but the secon is wider than the first, the third is wider than the second, and the fourth is wider than the third, the increase in width being proportional to the isothermic curves of the expansions of the steam. The lateral discs or side plates 7 of the various bucket wheels are at their periphery provided with several U-shaped teeth 7" which engage themselves between the teeth 8" of the periphery of the lateral rings 8' separating the various circles or series of stationary buckets of the casing from one another; the object of this arrangement is to revent the escape of steam from one of t e bucket wheels to the next. The buckets 7 of the rotor have a semi-cylindrical shape, while the buckets 8 of the casing have the sh-apeillustrated-in Fig. 1, e. g., approximately corresponding to that of the buckets 7, but somewhat shallower, their walls being inclined from about 25 to 30 in relation to the outer casing.

The stationary buckets immediately preceding those which correspond to the admission of the steam are provided with a gratelike obturator constituted by two super.- posed plates or sheets of metal 9 and 9 slotted or perforated-like a grate; they slide one on the other and are-moved b means of a rod 20 rotatably secured to eac of the plates 9 as shown at 20 and screw threaded on a portion of its length, the screw threaded portion extending throng-ha correspondingly threaded boss 21 of one of the sides of the outer casing of the turbine. The end of the rod 20 outside the turbine is fitted with ahandwheel 11 which when rotated causes the .plates 9 to slide against the" as packing preventing the steam from flowing from the admission nozzles directly to the passage 12 leading to the second expansion stage, and directly from the passage leading to such second expansion stage and-- to each subsequent expansion stage to the passage leading to the next expansion stage, the efficiency being then maximum, but whep said obturator is partially open it allows some. of the steam'so to bypass, the

' efiiciency being as a consequence correspondingly reduced. This obturator therefore provides a means of adjusting the efiiciency according to needs.

The reversibility of the direction of rotation of the turbine is obtained by means of a conical nozzle arranged in a direction 9' also opposite to that adopted for the rotationin' the forward'direction; the steam passes successively through the four bhcket wheels in a manner identical for the two directions of rotation; a second grate-like obtu'rator revents any return of steam when the turbine is reversed. The bottom of the buckets fitted, with the grate-like obturators is open in order to allow the passage of the steam. I

The turbine is very easy ofconstruction' as the rotor may becast in one piece; the same applies to the casing 4 provided with a reinforcing rib 5, whereas the construction of the turbines of the blade system is much longer and more complicate I The axial thrust in the present turbine is practically inexistent because of the way in which the steam acts on the circumference of the rotor, so that the use of thrust bear-- ings is not required and the efiiciency is therefore increased. A second outer-casing 6 encloses the machine thereby providing an air filled space or a space which may be filled with material suitable for preventing any loss of heat, so that the condensation of the steam within the turbine is avoided. 13 and- 14 are the steam inlet pipes for each of the directions of rotation of the turbine respectively.

Theturbine is' constructed so as to be adapted to work with a condenser.

I claim:

1. In a'multiple expansion reaction steam turbine, a plurality of rotary bucket-wheels of equal diameter each provided circumferentially with a plurality of semi-cylindrical buckets and of a width increasing proportionally to the isothermic curves of the expansions of the steam; in combination with a plurality of circumferential series of stationary buckets corresponding to the various bucket-wheels, secured tothe inner periphery of the turbine-casing; and each composed of a plurality of stationary buckets, equal in number to those of the corresponding bucket wheel and of a shape approximately corresponding to that of the last-named buckets but somewhat shallower, substantially as described.

k 2. In a multiple expansionreaction. steam turbine according to claim 1, an adjustable obturator fitted over' the two stationar buckets, immediately adjacent the two a i mission nozzles, of the lower sector of the turbine casing comprised between said two nozzles, said obturator consisting of twin superposed plates able to slide in relation to one another and having slots cut therein and so arranged that by said relative movement the slots in each plate may at will be caused to register with those of the other plate and to become gradually covered-up until entirely obturated by the solid portions of said other plate; and suitable handoperated means of known construction for effecting the adjustment of-said two in relation to' one another, substantia 1y as described. a

lates In testimony thereofI signed hereunto my name in the presence of two subscribing witnesses.

' ROGER DE POTTER. 

